Recognition of Handwritten ZIP Codes in a Real—WorldNon-Standard-Letter Sorting System

  • Authors:
  • M. Pfister;S. Behnke;R. Rojas

  • Affiliations:
  • Siemens AG, P.O. Box 4848, D-90327 Nuremberg, Germany;Freie Universität Berlin;Freie Universität Berlin

  • Venue:
  • Applied Intelligence
  • Year:
  • 2000

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Abstract

In this article, we describe the OCR and imageprocessing algorithms usedto read destination addresses from non-standard letters (flats) bySiemens postal automation system currently in use bythe Deutsche Post AG^1.We first describe the sorting machine, its OCR hardware and the sequence ofimage processing and pattern recognition algorithms needed to solvethe difficult task of reading mail addresses, especiallyhandwritten ones. The article concentrates mainly on the twoclassifiers used to recognize handprinted digits. One of them isa complex time delayed neural network(TDNN) used to classify scaled digit-features. The other classifierextracts the structure of each digit and matches it to a number of prototypes.Different digits represented by the same graph are then discriminated byclassifiying some of the features of the digit-graph with small neuralnetworks.We also describe some approaches for the segmentation of the digits in theZIP code, so that the resulting parts can be processed and evaluated by the classifiers.